Unions say they’re “seeking urgent answers” following reports Air Products is planning to halt work on its first energy-from-waste plant, threatening hundreds of Teesside jobs.

The US firm says the Seal Sands facility has not been mothballed and is still on track to come online at the end of the year.

But Unite union said todayit was trying to call an urgent meeting with bosses, after the firm appeared to have “gone to ground”.

One contract worker claimed some employees had been given notice to work until March 23 at the site and they had been told the plant was being mothballed while the firm sought a new investor.

The claims come four months after Air Products stopped construction at its second site (TV2) at North Tees Complex in Billingham, with the loss of 800 jobs.

Art George, from Air Products, said: “The TV1 site has not been mothballed. There has been no change in the TV1 status, nor the status with TV2; Air Products continues to work on starting up the TV1 facility, targeting the end of this year for commercial operation.

“Some contract workers have been released, but this is consistent with the type of work currently being carried out at TV1.

“As previously stated, we have identified learnings that are being implemented into the TV1 facility and we are currently in a period with higher engineering, design, and procurement activity and less activity in the field.

“We expect the activity in the field to again pick up in a few months.

“Like many companies, Air Products uses contract labour to supplement its own workforce during periods of high activity. When activity slows, contract labor is released to manage costs. All Air Products employees, including the employees hired to support the TV2 facility, continue to work at the site.”

But Steve Cason, Unite regional officer, said: “All we’ve got is complaints and mis-information - common sense would say ‘get the people round the table that need to be told’.

“We don’t know what’s going on at the moment.

“We have asked Air Products how many people they’re getting rid of, but they won’t tell us.”

He said the rumours were “extremely worrying”, coming so soon after the collapse of SSI, and the shutdown of works on Air Products’ second identical plant.

“If work stops at this site, hundreds of more highly skilled local jobs go with it. Teesside can ill-afford the collapse of yet another economically vital industry. It would be a hammer blow to the area and local economy, which is facing the loss of more than a thousand jobs from this firm alone in less than six months.”

The union was also seeking an urgent meeting with Stockton North MP, Alex Cunningham and the leader of Stockton Council, Bob Cook, he added.

“Unite will work tirelessly to protect the jobs of our members and to save this plant from being mothballed. Our members deserve answers.”

TV1, at the New Energy and Technology Business Park, is the UK’s largest power plant of its kind. It will convert pre-processed household, commercial and industrial waste into enough green energy to power the equivalent of 50,000 homes.